refactor: fetch join으로 n+1 제거

woowacourse-teams · Sep 20, 2023 · e9bbeee · e9bbeee
1 parent 4c747af
commit e9bbeee
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Showing 2 changed files with 10 additions and 2 deletions.
diff --git a/backend/src/main/java/com/festago/stage/repository/StageRepository.java b/backend/src/main/java/com/festago/stage/repository/StageRepository.java
@@ -2,6 +2,7 @@
 
 import com.festago.stage.domain.Stage;
 import java.util.List;
+import java.util.Optional;
 import org.springframework.data.jpa.repository.JpaRepository;
 import org.springframework.data.jpa.repository.Query;
 import org.springframework.data.repository.query.Param;
@@ -15,4 +16,12 @@ public interface StageRepository extends JpaRepository<Stage, Long> {
         WHERE s.festival.id = :festivalId
         """)
     List<Stage> findAllDetailByFestivalId(@Param("festivalId") Long festivalId);
+
+    @Query("""
+        SELECT s FROM Stage s
+        LEFT JOIN s.festival f
+        LEFT JOIN f.school sc
+        WHERE s.id = :id
+        """)
+    Optional<Stage> findByIdWithFetch(@Param("id") Long id);
 }
diff --git a/backend/src/main/java/com/festago/ticket/application/TicketService.java b/backend/src/main/java/com/festago/ticket/application/TicketService.java
@@ -33,7 +33,6 @@ public TicketService(TicketRepository ticketRepository, StageRepository stageRep
     public TicketCreateResponse create(TicketCreateRequest request) {
         Stage stage = findStageById(request.stageId());
         TicketType ticketType = request.ticketType();
-        // TODO: n+1
         School school = stage.getFestival().getSchool();
 
         Ticket ticket = ticketRepository.findByTicketTypeAndStage(ticketType, stage)
@@ -45,7 +44,7 @@ public TicketCreateResponse create(TicketCreateRequest request) {
     }
 
     private Stage findStageById(Long stageId) {
-        return stageRepository.findById(stageId)
+        return stageRepository.findByIdWithFetch(stageId)
             .orElseThrow(() -> new NotFoundException(ErrorCode.STAGE_NOT_FOUND));
     }